A dying doctor found his treatment, then built an engine for others

Idiopathic multicentric Castleman disease sends a patient's immune system into a storm that attacks their own organs, and by his fifth near-fatal flare every treatment tried, including the IL-6 blocker siltuximab, had failed to hold it off. He turned his own stored tissue and blood samples into his own research project.

Fajgenbaum's own lab work at the University of Pennsylvania found unusually high activity in a pathway called mTOR, and in 2014 he started taking sirolimus, an existing transplant drug that blocks that pathway, on himself. He has remained in remission since, a rare case of a physician's own research reaching his own bedside.

He later co-founded Every Cure, a nonprofit that applies the same logic systematically: scanning approved drugs and medical literature with AI for treatments already sitting on pharmacy shelves that could be repurposed for diseases they were never designed for. Castleman disease remains rare enough that sirolimus has only been studied in a handful of patients since, not yet in a large randomized trial.

One patient's remission became a search engine.